Penciclovir and Famciclovir are potent drugs used as virucides of herpes virus Eur-Pat. Appl. FP352, 953. Jan. 31, 1990: GB Appl. 88 17.607. 23 Jul. 1988. Nucleosides and Nucleotides, 1990 9 (4)499: Antiviral Chem. Chemother. 1993, 4(2)67!. The antiviral compounds viz. Penciclovir and Famciciovir are also used in the treatment of HIV-1 intentions PCT Int. Appl. WO9200742, 23 Jan. 1992!. The intermediates of formula (II) of the drawings, wherein R.sub.1.R.sub.2 .dbd.H.sub.3 C).sub.2 C. R.sub.3 .dbd.Br or O-tosyl: or R.sub.1 .dbd.R.sub.2 .dbd.Ac and R.sub.3 .dbd.Br: which are required for the 9-N-alkyl substitution in the synthesis of Penciclovir and Famciclovir have been prepared by reducing triethyl-1, 1, 2-ethane-tricarboxylate into 2-hydroxymethil butane-1, 4-diol Tetrahedron! lett. 1985, 26(35)4265, PCT Int. Appl. WO 9113, 162. 5 Sep. 1991, GB Appl., 90/4, 647 01 March 1990 followed by selective ketalizaton or acetylation. The novel compounds 9-hydroxymethyl-7,12-dioxaspiro5,6!dodecane of formula V and 9-(2-hydroxyethyl)-7, 11-dioxaspiro (5.5) undecane of formula VI of the drawings can be used with advantage for the 9-N alkyl substitution of the purines in order to make antiviral drugs like penciclovir and famciclovir. They are only intermediates and an independent use of these intermediates are not very obvious.
In our continuous research work in the area of carbonmonoxide chemistry, it was found that the crucial intermediate 9-(2-hydroxyethyl)-7, 11-dioxaspiro 5,5!undecane of the formula (VI) of the drawings accompanying the specification, which is useful for the synthesis of Penciclovir and Famciclovir can be prepared more efficiently starting with cis-but-2-ene-1, 4-dio and cyclohexanone through the formation of 7, 12-dioxaspiro 5,6!dodec-9-ene of the formula (III) of the drawings accompanying the specification, 9-formyl-7, 12-dioxaspiro5,6!dodecane of the formula (IV) of the drawings accompanying the specification and 9-hydroxymethyl-7, 12-dioxaspiro 5,6!dodecane of the formula (V) of the drawing accompanying the specification.